A multiple dwelling unit (MDU) is a structure, such as a hotel, apartment building, dormitory, or hospital, that provides individual accommodations and associated services to a number of occupants. The occupants may be relatively long term, as in an apartment building or dormitory, or short term, as in a hotel.
An operator of an MDU must provide access to certain essential services to the MDU's occupants, such as electricity, water, telephone, etc.
Different types of MDUs will use different technology to provide internal telephone service. An apartment building may provide a direct connection, typically via an unshielded twisted pair (UTP) of copper wires, from the local public switched telephone network (PSTN) to each unit, whereas a hotel may provide a connection, also via a UTP, from each unit to a private branch exchange (PBX). In a PBX based MDU, each telephone extension within the MDU connects to a central piece of PBX equipment and the PBX connects calls between the extensions, such as between a hotel room and the front desk. A number of trunk lines connect from the PBX to the local PSTN for making and receiving calls external to the MDU.
The local PSTN, or the PBX in conjunction with the local PSTN, provides analog voice communication and DC operating power for basic telephone services (POTS—Plain Old Telephone Service) over a UTP to each unit of an MDU. Depending on the quality and length of the UTP, the upper limit of the UTP's usable bandwidth can be upwards of 10 MHz, while POTS only utilizes the 0-4 kHz frequency band.
The operators of many MDUs also provide, or wish to provide, high-speed internet access (HSIA) to the MDU's occupants. A convenient method for providing HSIA to the units of an MDU is a version of digital subscriber loop (xDSL—x referring to any version of the DSL standard) technology. A key advantage of using xDSL technology is that it uses the existing telephone lines to provide HSIA without interfering with conventional telephone services.
The MDU as a whole may connect to the internet through an xDSL circuit connected to a local loop data circuit via a dedicated transmission line, such as a T1 line. On the MDU premises, multiple units may access the internet by connecting to the xDSL circuit, for instance embodied within a DSL access multiplexer (DSLAM). The DSLAM is connected to the MDU's internal phone lines between the PBX equipment and the units of the MDU. For network traffic entering the MDU, the DSLAM receives a high-bandwidth digital data signal from the local loop data circuit, demultiplexes the data signal according to the desired destination of the data (creating multiple lower bandwidth digital data signals), and modulates the digital data signals with a high-frequency analog waveform. The DSLAM then transmits the modulated digital data signal on to the appropriate unit's phone line, at higher frequencies than the conventional analog phone services, typically 30 kHz and above.
In the unit, an xDSL modem uses high-pass filter circuitry to isolate the high-frequency modulated data signals being transmitted over the phone line while any phone jacks not connected to the xDSL modem will use passive low-pass filter circuitry to isolate the lower frequency POTS signals, such as voice communication and dial tone signals and the DC operating power. The above process is reversed for outgoing network traffic. Typically, an xDSL modem receives DC operating power from a transformer/rectifier that converts AC power received from a 110-120 V 60 Hz wall outlet to low voltage DC power.
Operators of some MDUs such as hotels have found several frequently occurring barriers to successfully providing convenient and reliable xDSL based HSIA to the MDU's occupants. Frequently, components of the customer premises equipment, such as the xDSL modem's AC power supply or the xDSL modem's connection to the unit's phone line, can become disconnected, for instance by a hotel's cleaning staff or by the previous occupant of the unit. In addition, as most xDSL modems are small and operate independently from other equipment, theft of the xDSL modem and/or its AC power supply is also a problem. While these problems are not technically complicated to correct on a case-by-case basis, avoiding these issues entirely would clearly be preferable.
One possible deterrent to theft of the xDSL modem is to physically secure the xDSL modem to the MDU itself, for instance to a wall of the unit or to a large piece of furniture. However, the secured xDSL modem will still need be connected to the unit's phone line and to a power source and these connections may still inadvertently become unplugged causing an unnecessary service outage. If the connection between the phone line and the xDSL modem were inaccessible to occupants of the unit, the problem of disconnection of the phone line would be avoided. If operating power for the secured xDSL modem could also be provided in a way that is not readily accessible to an occupant of the unit, the problems of theft of the modem's AC power supply and the inadvertent disconnection of the AC power supply would also be avoided.
It is therefore desirable to provide an xDSL modem having means for connecting to an MDU unit's telephone line and means for providing operating power to the xDSL modem that are inaccessible to an occupant of the unit. It is also desirable that the design of the xDSL modem discourage theft. Further, it is also desirable that installation of the xDSL modem and any related components be simple and not require any replacement, removal or complex reconfiguration of existing telephone wiring.